But here's the thing. There's a bug - at least on iOS - where the progress of your wins against different opponents isn't getting updated. So if you want to earn the beach ball dice, KEEP A LIST OF THE PLAYERS YOU BEAT (and when) and then paste that information into a help request so customer service can give you credit for your achievement, as they did do for me. Thanks, Yahtzee!
Now here's my whole lineup of dice. I do expect this will be my final update, since the remaining locked dice involve tournaments and dice masters that are impossible to beat without spending moneys on bonus rolls. C'est la vie!